<template>
  <el-breadcrumb class="app-breadcrumb" separator="/">
    <transition-group name="breadcrumb">
      <el-breadcrumb-item v-for="(item, index) in levelList" :key="item.path">
        <span 
          v-if="index === levelList.length - 1" 
          class="no-redirect">
          {{ item.meta.title }}
        </span>
        <a v-else @click.prevent="handleLink(item)">
          {{ item.meta.title }}
        </a>
      </el-breadcrumb-item>
    </transition-group>
  </el-breadcrumb>
</template>

<script>
export default {
  name: 'Breadcrumb',
  data() {
    return {
      levelList: []
    }
  },
  watch: {
    $route: {
      handler(route) {
        this.getBreadcrumb()
      },
      immediate: true
    }
  },
  methods: {
    getBreadcrumb() {
      let matched = this.$route.matched.filter(item => item.meta && item.meta.title)
      const first = matched[0]

      if (!this.isAdminPage(first)) {
        matched = [{ path: '/admin', meta: { title: '首页' }}].concat(matched)
      }

      this.levelList = matched
    },
    isAdminPage(route) {
      if (!route) return false
      return route.path.startsWith('/admin')
    },
    handleLink(item) {
      const { path } = item
      this.$router.push(path)
    }
  }
}
</script>

<style scoped>
.app-breadcrumb.el-breadcrumb {
  display: inline-block;
  font-size: 14px;
  line-height: 50px;
  margin-left: 8px;
}

.no-redirect {
  color: #97a8be;
  cursor: text;
}

.breadcrumb-enter-active,
.breadcrumb-leave-active {
  transition: all .5s;
}

.breadcrumb-enter,
.breadcrumb-leave-active {
  opacity: 0;
  transform: translateX(20px);
}

.breadcrumb-move {
  transition: all .5s;
}

.breadcrumb-leave-active {
  position: absolute;
}
</style> 